Circuit structure for achieving adaptive function in class-D audio power amplifier circuit

Abstract

Disclosed is a circuit structure for implementing an adaptive function in a class-D audio power amplifier circuit, comprising an operation amplifier, a pulse width modulator and a driver stage that are sequentially and serially connected, an input terminal of the operation amplifier being connected to an external audio signal output terminal, and an output terminal of the driver stage being connected to a loudspeaker and connected to the input terminal of the operation amplifier via a feedback loop. The circuit structure further comprises: one or a plurality of a carrier adaptive circuit, a frequency adaptive circuit, a driver adaptive circuit, a temperature adaptive circuit.

What is claimed is: 
     
       1. A circuit structure for implementing an adaptive function in a class-D audio power amplifier circuit, the circuit structure comprising:
 an operation amplifier, a pulse width modulator and a driver stage that are sequentially and serially connected, an input terminal of the operation amplifier configured to be connected to an external audio signal output terminal, and an output terminal of the driver stage configured to be connected to a loudspeaker and connected to the input terminal of the operation amplifier via a feedback loop; 
 wherein the circuit structure further comprises a carrier adaptive circuit comprising:
 an input terminal configured to be connected to the external audio signal output terminal; and 
 an output terminal configured to be connected to an input terminal of the pulse width modulator, and 
 
 wherein the circuit structure further comprises a frequency adaptive circuit comprising:
 an input terminal configured to be connected to the external audio signal output terminal; and 
 an output terminal being respectively connected to the operation amplifier and the feedback loop. 
 
 
     
     
       2. The circuit structure of  claim 1 , wherein the carrier adaptive circuit further comprises an amplitude detector and a carrier generator that are sequentially and serially connected, wherein an input terminal of the amplitude detector is configured to be connected to the external audio signal output terminal, and wherein an output terminal of the carrier generator is connected to the input terminal of the pulse width modulator. 
     
     
       3. The circuit structure of  claim 2 , wherein the carrier generator is a frequency-adjustable carrier generator. 
     
     
       4. The circuit structure of  claim 1 , wherein the frequency adaptive circuit further comprises a frequency detector and a parameter selection register that are sequentially and serially connected, wherein an input terminal of the frequency detector is configured to be connected to the external audio signal output terminal, and wherein an output terminal of the parameter selection register is respectively connected to the operator amplifier and the feedback loop. 
     
     
       5. The circuit structure of  claim 4 , wherein the output terminal of the parameter selection register is connected to the operation amplifier via an adjustable capacitor and connected to the feedback loop via an adjustable resistor. 
     
     
       6. The circuit structure of  claim 1 , further comprising a driver adaptive circuit having:
 an input terminal connected to the output terminal of the driver stage; and 
 an output terminal connected to an input terminal of the driver stage. 
 
     
     
       7. The circuit structure of  claim 6 , wherein the driver adaptive circuit further comprises an edge detector and an adjustable driver circuit that are sequentially and serially connected, wherein an input terminal of the edge detector is connected to the output terminal of the driver stage, wherein an output terminal of the edge detector is connected to an input of the adjustable driver circuit, and wherein the adjustable driver circuit is further connected between an output terminal of the pulse width modulator and the input terminal of the driver stage. 
     
     
       8. The circuit structure of  claim 1 , further comprising a temperature adaptive circuit configured to be connected between the external audio signal output terminal and the input terminal of the operation amplifier. 
     
     
       9. The circuit structure of  claim 8 , wherein the temperature adaptive circuit comprises a temperature detector, a gain controller and an adjustable circuit network that are sequentially and serially connected, and wherein the adjustable circuit network is configured to be connected between the external audio signal output terminal and the input terminal of the operation amplifier. 
     
     
       10. The circuit structure of  claim 1 , further comprising:
 a driver adaptive circuit having an input terminal, connected to the output terminal of the driver stage, and an output terminal, connected to an input terminal of the driver stage; and 
 a temperature adaptive circuit configured to be connected between the external audio signal output terminal and the input terminal of the operation amplifier.